Natural gas furnaces, or gas-fired ovens, use naturally-occurring gaseous mixtures of hydrogen (H) and carbon (C) as the primary source of fuel. These hydrocarbons can be extracted from oil wells where they exist as off-gas, or they may be found in isolated natural gas fields and extracted using specialized drilling rigs. It is a fossil energy source that has more closely aligned with renewables compared to petroleum and coal, owing to its significantly reduced carbon emissions following combustion. As such, natural gas is dispensed to millions of homes around the world where it is used to fuel ovens and central heating systems that are more efficient than purely electric alternatives. It is also a common fuel source for furnaces in industrial spaces.
A natural gas furnace typically operates using a conventional burner, which uses a pilot light and a gas feed to produce a flame that is contained within a refractory burner tile. The fuel may be introduced as a pre-mix of natural gas and air or multiple feeds may supply pure fuel and primary air to produce a safe and steady flame. There are both benefits and drawbacks to this technology.
In this blog post, Thermcraft will explore some of the pros and cons of using a natural gas furnace in more detail.
Cost of Natural Gas Furnaces
The upfront cost of any furnace largely depends upon its scale, the complexity of its architecture, and any additional functionalities that your application might require. A natural gas furnace may be more expensive to install if it requires plumbing into a supply line – which is typically the case. Compressed natural gas (CNG) can be used if a supply line is unavailable.
Although more expensive upfront, natural gas furnaces are typically cheaper to run due to lower fuel costs and improved energy efficiency. A natural gas furnace will typically reach desired temperatures faster than an electrically-powered alternative, consuming significantly less fuel while heating-up. This results in appreciable savings in the long-term.
Performance Levels of Natural Gas Furnaces
A natural gas furnace will heat rapidly due to the direct generation of high-temperature combustion gas that is directed through a heating chamber using an air blower. Ceramic or carbon steel coils located within the furnace absorb this radiating heat and distribute it with high uniformity throughout the firebox. This design enables the rapid and highly-efficient generation of temperatures exceeding 1200°C (2192°F).
Thermcraft developed a custom gas-fired box furnace with six direct burners that could generate temperatures of 1260°C (2300°F) for a total of 2.4 million BTU’s. This performance is subject to the efficiency of each chamber in the natural gas furnace and the components used throughout. Steps should be taken to avoid direct flame impingement which can cause localized, over-heated spots on the radiant coils. This can cause structural fatigue which can only be addressed by replacing the element.
Emissions and Gas Generation in Natural Gas Furnaces
The primary drawback of natural gas furnaces is the generation of emissions and the potential for cross-contamination of samples. Burning any fossil fuel raises carbon monoxide (CO) safety concerns which can be harmful to personnel. Flue gases must also be carefully contained or vented in compliance with regulatory standards, and potential leaks must be identified and eliminated to ensure the safety of plant operators.
Given the unavoidable generation of process gases and particulates, natural gas furnaces are typically unsuitable for heat treatment of chemically-sensitive products. However, electrical furnaces often utilize natural gas curtain burners around controlled-environment heating chambers to maintain the purity of inert atmospheres.
Natural Gas Furnaces from Thermcraft
Thermcraft is one of the world’s leading suppliers of industrial furnaces for the preparation of intermediate or end products. We offer a broad range of custom heat treatment solutions, including natural gas furnaces and electrical ovens with additional combustion-based controls.
If you would like any more information about our natural gas furnaces, please do not hesitate to contact us.